There has been continuous movement in carrier industries, particularly with respect to air carriers, to improve and enhance passenger safety, particularly in the area of regulatory compliance. Passenger seats must pass through a number of regulatory tests and certifications before they may be installed in commercial vehicles. As a result, there is a push for new technologies to improve passenger safety in survivable crashes and maintain regulatory compliance by passing all applicable safety testing.
Passenger seats have traditionally been rigidly mounted to a cabin floor or other support structure within the vehicle. Rigid mounting of seats improves passenger confidence and comfort. However, during an emergency such as a survivable crash, deformation of the cabin floor or support structures can lead to excessive loading and separation of the passenger seat attachment points from the cabin floor or support structures. Separation of the passenger seats from the cabin floor or support structures not only results in reduced survivability for passengers, but fails to meet certain regulatory requirements. In particular, Federal Aviation Administration guidelines contained within 14 C.F.R. 25.562, sometimes referred to as the 16G Pitch and Roll Test, mandate that a seat mounting may not separate from a cabin floor in the event of a distortion of the cabin floor equivalent to a ten degree pitch and ten degree roll.
In certain cases, it may be desirable to provide a passenger seat with an extendable joint between the passenger seat frame and the cabin floor or support structure. The extendable joint, which is preloaded or otherwise restricted to prevent motion in normal circumstances, allows the passenger seat legs or frame to extend and move with the cabin floor or support structure when it deforms. The extension of the passenger seat frame or leg absorbs and distributes the forces applied to the passenger seat over a longer period of time and a greater range of motion. The result is decreased loading of the seat to floor attachment points and seat frame resulting in a reduced likelihood of separation between the passenger seat and the cabin floor, or failure of other parts of the passenger seat frame. The extendable joint also provides opportunities for additional components, such as crushable inserts or springs, that may be used to further absorb forces resulting from a crash or emergency situation.